An apparatus for and method of measuring pressure through a septum in a patient's heart is disclosed. A lead inserted into the right side of a heart is routed through the septum to gain access to the left side of the heart. The lead includes an attachment structure that secures the lead to one or both of the septal walls. The attachment structure may include at least one protruding tine, membrane, inflatable balloon, involuted spiral or J-lead that engage one or more sides of the septum. The lead also includes one or more sensors for measuring cardiac pressure on the left side of the heart and, as necessary, the right side of the heart.